<template>
    <transition name="el-zoom-in-top" @after-leave="$emit('dodestroy')">
        <div
                v-show="visible"
                class="el-picker-panel el-date-range-picker el-popper"
                :class="[{
        'has-sidebar': $slots.sidebar || shortcuts
      }, popperClass]">
            <div class="el-picker-panel__body-wrapper">
                <slot name="sidebar" class="el-picker-panel__sidebar"></slot>
                <div class="el-picker-panel__sidebar" v-if="shortcuts">
                    <button
                            type="button"
                            class="el-picker-panel__shortcut"
                            v-for="(shortcut, key) in shortcuts"
                            :key="key"
                            @click="handleShortcutClick(shortcut)">{{shortcut.text}}
                    </button>
                </div>
                <div class="el-picker-panel__body">
                    <div class="el-picker-panel__content el-date-range-picker__content is-left">
                        <div class="el-date-range-picker__header">
                            <button
                                    type="button"
                                    @click="leftPrevYear"
                                    class="el-picker-panel__icon-btn el-icon-d-arrow-left"></button>
                            <button
                                    type="button"
                                    v-if="unlinkPanels"
                                    @click="leftNextYear"
                                    :disabled="!enableYearArrow"
                                    :class="{ 'is-disabled': !enableYearArrow }"
                                    class="el-picker-panel__icon-btn el-icon-d-arrow-right"></button>
                            <div>{{ leftLabel }}</div>
                        </div>
                        <month-table
                                selection-mode="range"
                                :date="leftDate"
                                :default-value="defaultValue"
                                :min-date="minDate"
                                :max-date="maxDate"
                                :range-state="rangeState"
                                :disabled-date="disabledDate"
                                @changerange="handleChangeRange"
                                @pick="handleRangePick">
                        </month-table>
                    </div>
                    <div class="el-picker-panel__content el-date-range-picker__content is-right">
                        <div class="el-date-range-picker__header">
                            <button
                                    type="button"
                                    v-if="unlinkPanels"
                                    @click="rightPrevYear"
                                    :disabled="!enableYearArrow"
                                    :class="{ 'is-disabled': !enableYearArrow }"
                                    class="el-picker-panel__icon-btn el-icon-d-arrow-left"></button>
                            <button
                                    type="button"
                                    @click="rightNextYear"
                                    class="el-picker-panel__icon-btn el-icon-d-arrow-right"></button>
                            <div>{{ rightLabel }}</div>
                        </div>
                        <month-table
                                selection-mode="range"
                                :date="rightDate"
                                :default-value="defaultValue"
                                :min-date="minDate"
                                :max-date="maxDate"
                                :range-state="rangeState"
                                :disabled-date="disabledDate"
                                @changerange="handleChangeRange"
                                @pick="handleRangePick">
                        </month-table>
                    </div>
                </div>
            </div>
        </div>
    </transition>
</template>

<script type="text/babel">
    import {
        isDate,
        modifyWithTimeString,
        prevYear,
        nextYear,
        nextMonth
    } from 'element-ui/src/utils/date-util';
    import Clickoutside from 'element-ui/src/utils/clickoutside';
    import Locale from 'element-ui/src/mixins/locale';
    import MonthTable from '../basic/month-table';
    import ElInput from 'element-ui/packages/input';
    import ElButton from 'element-ui/packages/button';

    const calcDefaultValue = (defaultValue) => {
        if (Array.isArray(defaultValue)) {
            return [new Date(defaultValue[0]), new Date(defaultValue[1])];
        } else if (defaultValue) {
            return [new Date(defaultValue), nextMonth(new Date(defaultValue))];
        } else {
            return [new Date(), nextMonth(new Date())];
        }
    };
    export default {
        mixins: [Locale],

        directives: {Clickoutside},

        computed: {
            btnDisabled() {
                return !(this.minDate && this.maxDate && !this.selecting && this.isValidValue([this.minDate, this.maxDate]));
            },

            leftLabel() {
                return this.leftDate.getFullYear() + ' ' + this.t('el.datepicker.year');
            },

            rightLabel() {
                return this.rightDate.getFullYear() + ' ' + this.t('el.datepicker.year');
            },

            leftYear() {
                return this.leftDate.getFullYear();
            },

            rightYear() {
                return this.rightDate.getFullYear() === this.leftDate.getFullYear() ? this.leftDate.getFullYear() + 1 : this.rightDate.getFullYear();
            },

            enableYearArrow() {
                return this.unlinkPanels && this.rightYear > this.leftYear + 1;
            }
        },

        data() {
            return {
                popperClass: '',
                value: [],
                defaultValue: null,
                defaultTime: null,
                minDate: '',
                maxDate: '',
                leftDate: new Date(),
                rightDate: nextYear(new Date()),
                rangeState: {
                    endDate: null,
                    selecting: false,
                    row: null,
                    column: null
                },
                shortcuts: '',
                visible: '',
                disabledDate: '',
                format: '',
                arrowControl: false,
                unlinkPanels: false
            };
        },

        watch: {
            value(newVal) {
                if (!newVal) {
                    this.minDate = null;
                    this.maxDate = null;
                } else if (Array.isArray(newVal)) {
                    this.minDate = isDate(newVal[0]) ? new Date(newVal[0]) : null;
                    this.maxDate = isDate(newVal[1]) ? new Date(newVal[1]) : null;
                    if (this.minDate) {
                        this.leftDate = this.minDate;
                        if (this.unlinkPanels && this.maxDate) {
                            const minDateYear = this.minDate.getFullYear();
                            const maxDateYear = this.maxDate.getFullYear();
                            this.rightDate = minDateYear === maxDateYear
                                ? nextYear(this.maxDate)
                                : this.maxDate;
                        } else {
                            this.rightDate = nextYear(this.leftDate);
                        }
                    } else {
                        this.leftDate = calcDefaultValue(this.defaultValue)[0];
                        this.rightDate = nextYear(this.leftDate);
                    }
                }
            },

            defaultValue(val) {
                if (!Array.isArray(this.value)) {
                    const [left, right] = calcDefaultValue(val);
                    this.leftDate = left;
                    this.rightDate = val && val[1] && left.getFullYear() !== right.getFullYear() && this.unlinkPanels
                        ? right
                        : nextYear(this.leftDate);
                }
            }
        },

        methods: {
            handleClear() {
                this.minDate = null;
                this.maxDate = null;
                this.leftDate = calcDefaultValue(this.defaultValue)[0];
                this.rightDate = nextYear(this.leftDate);
                this.$emit('pick', null);
            },

            handleChangeRange(val) {
                this.minDate = val.minDate;
                this.maxDate = val.maxDate;
                this.rangeState = val.rangeState;
            },

            handleRangePick(val, close = true) {
                const defaultTime = this.defaultTime || [];
                const minDate = modifyWithTimeString(val.minDate, defaultTime[0]);
                const maxDate = modifyWithTimeString(val.maxDate, defaultTime[1]);
                if (this.maxDate === maxDate && this.minDate === minDate) {
                    return;
                }
                this.onPick && this.onPick(val);
                this.maxDate = maxDate;
                this.minDate = minDate;

                // workaround for https://github.com/ElemeFE/element/issues/7539, should remove this block when we don't have to care about Chromium 55 - 57
                setTimeout(() => {
                    this.maxDate = maxDate;
                    this.minDate = minDate;
                }, 10);
                if (!close) return;
                this.handleConfirm();
            },

            handleShortcutClick(shortcut) {
                if (shortcut.onClick) {
                    shortcut.onClick(this);
                }
            },

            // leftPrev*, rightNext* need to take care of `unlinkPanels`
            leftPrevYear() {
                this.leftDate = prevYear(this.leftDate);
                if (!this.unlinkPanels) {
                    this.rightDate = prevYear(this.rightDate);
                }
            },

            rightNextYear() {
                if (!this.unlinkPanels) {
                    this.leftDate = nextYear(this.leftDate);
                }
                this.rightDate = nextYear(this.rightDate);
            },

            // leftNext*, rightPrev* are called when `unlinkPanels` is true
            leftNextYear() {
                this.leftDate = nextYear(this.leftDate);
            },

            rightPrevYear() {
                this.rightDate = prevYear(this.rightDate);
            },

            handleConfirm(visible = false) {
                if (this.isValidValue([this.minDate, this.maxDate])) {
                    this.$emit('pick', [this.minDate, this.maxDate], visible);
                }
            },

            isValidValue(value) {
                return Array.isArray(value) &&
                    value && value[0] && value[1] &&
                    isDate(value[0]) && isDate(value[1]) &&
                    value[0].getTime() <= value[1].getTime() && (
                        typeof this.disabledDate === 'function'
                            ? !this.disabledDate(value[0]) && !this.disabledDate(value[1])
                            : true
                    );
            },

            resetView() {
                // NOTE: this is a hack to reset {min, max}Date on picker open.
                // TODO: correct way of doing so is to refactor {min, max}Date to be dependent on value and internal selection state
                //       an alternative would be resetView whenever picker becomes visible, should also investigate date-panel's resetView
                this.minDate = this.value && isDate(this.value[0]) ? new Date(this.value[0]) : null;
                this.maxDate = this.value && isDate(this.value[0]) ? new Date(this.value[1]) : null;
            }
        },

        components: {MonthTable, ElInput, ElButton}
    };
</script>
